Marking compound



Patented Jan. 22, 1935 -m ipmm @o F:F -ic-E i v ism-'12s I i I imammin QAQplicationJuly 24,1931

(Cl. 13148 I 5 which will not interfere with the :unifoim areception of the carbon icoatingronithe surface of paper after 1-it lhas been marked.

In the manufacture of carbon paper, itis sometimes desii able to place amark =bn' the back of each sheet to indicate tne qualitypgiao use,

or rother characteristics the'reof.

-Since the majority of :carbon papers of iihe bestvquaiity are usually made on dark coloured tissues, or on very absorbent papers, -which5allowthemarbon ink to soak through whilekhoa in' the coating process, thus giving the urrcoated side or the carbon paper a dark appearance, itis desirable that the :markingLbe or light colored, in

order that it may be clearly legible.

It is also very essential that the compound used in marking should not so affect the paper by impregnation, soaking through or otherwise is uneven or different from the surrounding area.

As absorption of carbon ink only affects the liquid part of the ink and not the pigment colors which furnish the writing strength, it is highly necessary that absorption be uniform, otherwise any area which absorbed less of the liquid part of the ink leaves the ink in the affected area with a lower percentage of pigment, writing or copying material, thus giving an uneven writing. This effect occurs when a marking material is used that in any way affects the capillary action of the paper or affects the fluidity of the ink itself.

In the marking of carbon paper it is sometimes customary to mark the paper with a trade mark or design before coating it with carbon ink, as in my Patent #l,780,007, which covers the use of an alkaline solution applied on the same side as, and before, the application of the carbon ink. The effect being that the alkali saponifies the carbon ink so that it will not penetrate the paper, leaving the marked design much lighter in shade than the surrounding area.

Others have attempted to apply the design with a material which presents a solid barrier to the subsequently applied carbon ink, thus rendering the paper in the barrier area lighter in color than the surrounding area, due to a reduction in absorptive power in the paper.

I consider my new iinventionl'mucnsuperior to" either of the above, as ith'e paper is in ino way -aflected. iin absorptive power in the marked area. The papersx'usedfasa basis tor a carbon papers are usually veryothin, and ithe coat ing ofrcarbon ink, when applied, should be uniformly absorbed through the paper throughout its entire area. :If fthe ip'oper :base has been rendered nonabsorbent in certain areas by. the application-and penetration of a marking compound, which renders a pa er-more: r less impervious :in such areassoas to prevent-the same absorption of the carbon as in the areas not marked,f-there resultsaniuneven coatingand aflconsequent nonuniformity copyingpower-pr Jcapacity, it is best to-accomplish this result by using amarkring compound that: will not re'nder int-he pa er imperviousmtovcarbon: ink absorptioniand .towapply an extremely small amount for such markings. This I accomplish by using a vehicle having a small proportion of non-drying and non-volatile oil and a relatively large proportion of a volatile solvent miscible with the oil, to which is added a relatively small proportion of pigment or coloring material.

Carbon inks consists mainly of a composition of waxes, anilin dyes, and pigment colors,- the pigment being relied upon to furnish the chief marking compound. It is, therefore, desirable to have as great a proportion of pigmenton the surface of the carbon paper as possible. This proportion can be greatly increased if any given ink, containing pigment colors, is applied to carbon tissues while hot and liquid, and then run at such slow speed and over hot rolls as will permit as much non-pigment part of the ink to absorb into the paper, thus leaving on the surface a heavier concentration of the pigment color. If the nature of the marking material used is such that it will fill up the pores of the paper permanently, it will prevent the absorption of the liquid part of the carbon ink in such areas, so that there will be a diiference in pigment content tending towards lack of uniformity in writing of the carbon paper.

The result of the use of my new mixture is that while there is sufiicient fluidity imparted to the marking compound by the thinning action of the solvent, there is present only a sufficient quantity of the non-volatile and non-drying oil to form a binder to hold together and to the paper the minute particles of the pigment, or to hold the coloring matter to the paper without so impregnating the paper as to prevent its receiving a substantially uniform coating of the carbon ink. Since the layer of marking compound is preferably as thin as possible, it is essential that the pigment or coloring matter used in the compound shall have a maximum of hiding power in order to produce an easily legible mark. I find that oxide of titanium makes a white pigment of great hiding power and may, therefore, be applied in very minute quantities to produce a clearly legible mark on any background either light or dark.

For example, I find the following formula given in parts by weight to be one which successfully embodies the spirit of my invention.

Mix one part finely pulverized titanium oxide, one part of non-drying, non-volatile, light-c01- ored mineral oil, such as spindle oil or paraffin oil, and four parts of mineral spirits or other volatile solvent miscible with the oil used. I also find that a pigment containing precipitated titanium oxide gives good results when substituted either in whole or in part for the titanium oxid mentioned in the above formula. 1

Although titanium oxide or a pigment containing precipitated titanium oxide, or a combination of them, give excellent results, I find .that other pigments may also be used, such as zinc oxide, blanc fixe, lithopone, and other white or light-colored pigments. I may also use colored pigments such as chrome yellow and other pigments of suitable tinting power.

By means of a marking compound of this type, I find that I can mark carbon paper either immediately before or immediately after the carbon ink is applied to one of its surfaces with a marking mechanism attached to the coating machine, and that it is not necessary to make a separate operation of the marking of the paper nor to run the paper through a marking machine prior to running it through the coating machine. Furthermore, I find that by the application of my new marking compound it now becomes possible to place a large design, picture or other marking which may substantially cover the entire back of the carbon paper sheet without interfering with or lessening the uniformity or copying quality of the sheet.

I have stated that I use mineral oil of a nondrying, non-volatile type; but I may also use a vegetable or animal oil in place of the mineral oil. I may use various volatile thinners, either alone or in combinations, such as petroleum distillates or coal tar distillates, or wood tar distillates, or turpentine, or organic compounds of the alcohol series, or substances having equivalent characteristics as regards rate of evaporation, miscibility with the oil used and peneenabling one skilled in the art to make and use the same, .I now state what I believe to be new and for which I-pray that Letters Patent be granted:

A marking compound for marking carbon paper,. composed of titanium oxide one part, mineral oil two parts, petroleum spirits four parts, all by weight.

' HAROLD W. A. DIXON. 

